The genetic and neural control of higher behaviors in Drosophila are being analyzed by studying perturbations of the central nervous systems, and by experiments on biochemical substances that contribute to the control of these behaviors. Genetic variants affecting fixed action patterns in reproductive behavior have allowed a dissection of the many steps involved in male-female interactions. Behavioral and histochemical experiments on genetic mosaics will be done, to probe further the parts of the central nervous system which mediate the initiation of courtship, and subsequent quantifiable steps such as species-specific wing vibration. A particular portion of the brain controls courtship initiation by males, and this region probably processes olfactory infcrmation coming from females. A portion of the thoracic nervous system must be male for normal wing vibration. These portions of the anterior and posterior ganglia will be further studied, by behavioral analysis of courting flies that carry specific defects induced by neurochemical mutants. Female-specific behavior will be studied in genetic mosaics, to analyze which portions of the CNS must carry 2 X chromosomes in order that normal courtship and post-mating behaviors occur. One component of post-mating behavior may involve centrally conditioned actions, since we have found that a Drosophila "memory" mutant has defective interactions with mated females. Other learning and memory mutants will be studied to pursue this discovery of "non-innate" control of part of the courtship fixed action patterns. The features of these experiments which bear on putative pheromones involved in courtship initiation or post-mating behaviors will be studied further. We have extracted and analyzed chromatographically male-specific and female-specific compounds, and shown the latter to be biologically active. We will further purify the volatile compounds which are particularly active, study their physiological effects (bearing on how the information is received by the flies and then processed by the CNS), and study chromatographically certain behavioral mutants which appear to have altered amounts or quality of these putative pheromones.